We are grateful to our friends at Traditional Catholic for their extensive research in finding the following resources.
Gregorian chant – Benedictines of St. Benoit du Lac
Gregorian chant – Benedictines of Silos
Gregorian chant – Benedictines of Ligugé – CD 1 & CD 2
Gregorian chant of Assisi (Medieval lauds)
Gregorian chant – Abbey of Grimbergen
Old Roman chant of the 6th century – Ensemble Organum (16 audios)
Popular Gregorian hymns – Abbey of Notre-Dame de Timadeuc
Cistercian chant – Abbey of Flaran
Gregorian chant – Benedictine monks of St. Michel
Campus Stellae: Sacred chant of the 12th century
Codex Calixtinus: Ad Vesperas Sancti Jacobi – Ensemble Organum
Gregorian chant (Franciscan manuscripts of the 17-18th cent.) – Ensemble Organum
Monastic chant of the 12th and 13th century
Gregorian Chant: Monastic Choir of the Abbey of St. Pierre de Solesmes